Aircraft are increasingly including electric motors to drive various system components, rather than presently or previously used pneumatic or hydraulic motors or other devices. For many aircraft systems, regulatory agencies have established guidelines for system design to accommodate postulated, yet highly unlikely events, such as a component within the system becoming unavailable or otherwise inoperable. In many instances, the established guidelines require that a system be designed to “fail passive” in the face of such postulated, yet highly unlikely events.
In order to increase reliability and fault tolerance, and to meet the established regulatory guidelines, many electric motor control systems include redundant motor controls. One such motor control system is disclosed in U.S. Pat. No. 6,573,672 (the '672 patent), entitled “Fail Passive Servo Controller,” which is assigned to the assignee of the instant application. The motor control disclosed in the '672 patent implements a polarity voting scheme between redundant brushless motor control lanes. The disclosed polarity voting scheme is well-suited for a trapezoidal commutation scheme. However, it is not at all well-suited for non-trapezoidal commutation schemes, such as field oriented control (FOC)/space vector modulation (SVM) or sinusoidal commutation control. As is generally known, non-trapezoidal commutation schemes provide smoother motor torque control than trapezoidal commutation control schemes.
Accordingly, it is desirable to provide a motor control system and method that implements non-trapezoidal motor control and that meets established “fail passive” regulatory guidelines. The present invention addresses at least this need.